1. Field
The invention(s) relate to optical communication equipment and, more specifically but not exclusively, to equipment for managing data transport through a nonlinear and/or noisy optical channel.
2. Description of the Related Art
This section introduces aspects that may help facilitate a better understanding of the invention(s). Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Forward error correction (FEC) uses systematically generated redundant data to reduce the bit-error rate (BER) at the receiver. The cost of this reduction is a concomitant increase in the required forward-channel bandwidth, the latter being dependent on the overhead of the FEC code. In general, an FEC code with a larger overhead or lower net data rate is used for a noisier channel. When the channel conditions change over time, the net data rate and/or the FEC code can be adaptively changed to maintain an acceptable BER. However, one problem with FEC coding, as applied to optical transmission systems, is that the coding-gain differences among various implementable FEC codes usually do not exceed a certain maximum value, as given by Shannon's information capacity theory. In addition, the digital signal processing (DSP) complexity for capacity-approaching FEC codes can be forbiddingly high. Therefore, for certain optical channels, additional and/or alternative performance-enhancement techniques may be needed to overcome these and other pertinent limitations of FEC coding.